1. Field of the Invention
The present invention relates to novel pseudoerythromycin derivatives or salt thereof.
2. Description of Related Art
Erythromycin (hereinafter sometimes designates as EM) has been used for long time as 14-membered macrolide antibiotic for treatment of infectious disease caused by Gram-positive bacteria. During past ten and several years, erythromycin has known to improve long-term chronic inflammatory diseases such as diffuse panbronchiolitis and bronchial asthma, except for therapeutic action to bacterial infectious diseases. (Kudo, Shojli et al., Studies of clinical results on long term small administration of erythromycin for diffuse panbronchiolitis-Treatment results for 4 years, J. Japan. Thorac. Dis. Assoc., 25: 632-642, 1987).
Erythromycin is an antibiotic and has antibacterial action which is not always required for treatment of inflammatory diseases. Consequently, resistant bacteria are generated in patients who are administered antibiotics, as a result, it causes deterioration for treatment of infectious disease in the other occasion.
As described above, Kudo, Shoji et al. demonstrated that diffuse panbronchiolitis could be improved by long term small administration of erythromycin (Kudo, Shoji et al., Studies of clinical results on long term small administration of erythromycin for diffuse panbronchiolitis-Treatment results for 4 years, J. Japan. Thorac. Dis. Assoc., 25: 632-642, 1987).
Recently, actions other than antibiotic activity of erythromycin is noted, as a result, usefulness other than pulmonary region, for example not limited in diffuse panbronchiolitis but for chronic sinusitis and Crohn""s disease are reported. The mechanism of action of erythromycin for chronic disease such as diffuse panbronchiolitis is thought to be the result of original antibacterial action. Research studies are now ongoing, and indicate the antiinflammatory action mediated by immune inflammatory cells in the penumbral chronic respiratory tract inflammation.
For example, the studies indicate the regulation for migration of neutrophils to infectious region by direct action, and the regulation for migration of neutrophils or for release of active oxygen from neutrophils by indirect action through mediators or cytokines. Further, erythromycin has an action to lymphocytes, macrophages and mast cells to regulate their proliferation or cytokine production, or to induce differentiation. (Kudo, Shoji Ed., Supervisors: Shimizu, Kihachiro and Omura Satoshi xe2x80x9cInflammation, Immunity and Macrolides Up to Datexe2x80x9d, Iyaku Journal Inc., Osaka, 1996)
As explained above, 14-membered macrolides are thought to cure chronic respiratory diseases as a result of exhibiting immune regulation and antiinflammatory action.
We have aimed at the promoting action of erythromycin for differentiation-induction frommonocyte to macrophage (N. Keicho, S. Kudoh, H. Yotsumoto, K. Akagawa, xe2x80x9cErythromycin promotes monocyte to macrophage differentiationxe2x80x9d, J. Antibiotics, 47, 80-89, 1994), and tried to synthesize erythromycin derivatives for the purpose of creating the derivatives having disappeared antibacterial action and enhanced promoting action for differentiation-induction.
The present invention relates to a novel pseudoerythromycin derivative represented by the general formula [I], 
wherein R1 and R2 are same or different and each represents H, alkyl, alkynyl, acyl, or sulfonyl, in which these groups may optionally have substituents, and Me indicates methyl.
Further, the present invention relates to a novel pseudoerythromycin derivative represented by the general formula [II], 
wherein R is heterocyclic containing N which may optionally have substituents, and Me indicates methyl.
The present invention further relates to a novel pseudo erythromycin derivative represented by the general formula [III], 
wherein R3 is O or NOH, and Me indicates methyl.
The invention further relates to a novel pseudoerythromycin derivative represented by the general formula [IV], 
wherein R1 and R2 are same or different and each represents H or methyl, R3and R4represent H, hydroxyl or amino, and Me indicates methyl.
The present invention further relates to a novel pseudo erythromycin derivative represented by the general formula [V], 
wherein R1 and R2 are same or different and each represents H or methyl, and Me indicates methyl.
Synthetic methods of various erythromycin derivatives are, for example, illustrated in the synthetic scheme as shown in FIG. 1. Namely, erythromycin A is treated with ice-cold acetic acid according to the references: (a) I. O. Kibwage, R. Busson, G. Janssen, J. Hoogmartens, H. Vanderhaeghe, Translactonization of Erythromycins, J. Org. Chem., 52, 990-996, 1987, (b) H. A. Kirst, J. A. Wind, J. W. Paschal, Synthesis of Ring-Constracted Derivatives of Erythromycin, J. Org. Chem., 52, 4359-4362, 1987, introducing to erythromycin A enol ether (EM 201), subsequently refluxing in methanol with heating in the presence of potassium carbonate to introduce pseudoerythromycin A enol ether (EM701) (known compound).
The product was treated with iodine and sodium acetate according to the reference (L. A. Friberg, U.S. Pat. No. 3,725,385) to obtain de-N-methyl-pseudoerythromycin A enol ether (EM703) (known compound). The compound was further treated with iodine and sodium methoxide to obtain bis(de-N-methyl)-pseudo erythromycin A enol ether (EM721) (novel compound). Alkylation, acylation and sulfonylation using EM703 and EM721 resulted to synthesize various derivatives through bis-de(3xe2x80x2-N-methyl)-3xe2x80x2-N-ethyl-8,9-anhydro-pseudoerythromycin A 6,9-hemiketal (EM722).
The synthetic scheme of compounds of the present invention is illustrated in FIG. 1. Namely, the compounds can be obtained by the synthetic route of: erythromycin A (EMA)xe2x86x92erythromycin A enol ether (EM201)xe2x86x92pseudoerythromycin A enol ether (EM701)xe2x86x92de-N-methyl-pseudoerythromycin A enol ether (EM703)xe2x86x92bis (de-N-methyl)-pseudoerythromycin A enol ether (EM721).
In order to confirm enhancing effect for differentiation-induction of the compounds of the present invention, the enhancing effect for differentiation-induction from human monocyte to macrophage was assayed. Method is performed as follows.
THP-1 cells were collected from cultured liquid by centrifugation, adjusted the concentration to 2xc3x97105 cells/ml using medium (RPMI 1640) and distributed into the 48-well plate at 500 xcexcl/well. PMA solution 10 xcexcl and sample solution 5 xcexcl were added in each well, stirred with mild shaking and incubated at 37xc2x0 C. for 72-96 hours under 5% CO2. Further MTT 0.5 mg/ml solution was added at 300 xcexcl/well, and incubated at 37xc2x0 C. for 3 hours under 5% CO2. Supernatant solution was suctioned using the injection tube, added DMSO 500 xcexcl using automatic continuous injector to dissolve formazan completely and transferred each 100 xcexcl to the 96-well plate. The optical absorption was measured using the plate-reader.
Results of the enhancing effect for differentiation-induction from human monocyte to macrophage measured by the above assay method are shown in Table 1.
In Table 1: Me: methyl; Pr: propyl; Et: ethyl; Ac: acetyl; and Ms: methanesulfonyl. *ED50: Drug concentration (xcexcM) required for 50% differentiation-induction of THP in Mxcfx86.
In Table 1, indicated activity is represented in comparison with enhancing action for differentiation-induction of EM 100 xcexcM and symbols are: ++: enhanced 100% or more; +: enhanced 50-100%; xc2x1: enhanced 25-50%; xe2x88x92: no activity; /: expressed cytoxicity; and NT: not tested or under assessment.
As shown in Table 1, since the smaller the value of ED50 (xcexcM), (minimum drug concentration required for 50% differentiation-induction from THP-1 to Mxcfx86), the stronger the differentiation-induction activity, it was found that the compounds of the present invention have enhancing action for diffferentiation-induction from THP-1 to Mxcfx86.
Next, the suppressive effect of the compound of the present invention (EM703) against bleomycin-induced pulmonary fibrosis was examined (hereinafter sometimes designates bleomycin as BLM).
A sample suspended in 5% gum arabic was orally administered, 50 mg/kg/day for 17 days (from day-3 to day-13), and bleomycin, 100 mg/kg, was administered from tail vein in day-0. On day-28, animals were sacrificed under anesthesia and fibrosis of the lungs was compared with non-administered mice. Suppressive effects are shown in Table 2.
Azuma A., Furuta T., Enomoto T., Hashimoto Y., Uematsu K., Nukariya N., Murata A., Kudoh S., Preventive effect of erythromycin on experimental bleomycin-induced acute lung injury in rats Thorax 53, 186-189, 1998
As indicated above, hydroxyproline is an index of lung fibrosis and higher value indicates hyperfibrosis. Hydroxyproline level, an index for lung injury, in BLM administered group was reduced in a group of BLM+EM703.
Next, the suppressive effect of the compound EM703 against pneumonia caused by influenza viral infection was examined.
Sample was dissolved in physiological saline containing 1% DMSO and amount corresponding to oral dosage of the small administration for long-term therapy was administered from day-1 to day-6 of the infection to mice influenza pneumonia model (0.3 mg and 0.03 mg/mice), once a day, intraperitoneally. Results were compared with control group which was given only solvent.
Sato K., Suga M., Akaike T. et al., Therapeutic effect of erythromycin on influenza virus-induced lung injury in mice. Am. J. Respir Crit. Care Med. 157, 853-859, 1998.
Results are shown in FIG. 2 and FIG. 3. In this system, mice developed pneumonia and almost died about 20 days after infection. Contrary to that, as shown in FIG. 2, administration of EM703, 0.3 mg/mice, cured pneumonia and 40% of mice were survived. Further, as shown in FIG. 3, mice without administration of drugs (control) indicated significant decrease of body weight due to pneumonia, but administration of EM703 indicated to increase body weight from day-10. This indicates suppressive effect against pneumonia and result to cure pneumonia.
As described above, the compound of the present invention shows suppressive effect against influenza virus-induced pneumonia.